Trunking between SG300 and SG200

[pektron77]

Hi, I'm having difficulties with trunking between a SG300 and SG200.

We have a network of several switches that previously didn't use VLAN's so I brought in the SG300 and created a VLAN with ID 10 on the SG300.  To extend VLAN 10 I then made the port connecting one of the edge switches a Trunk port with Vlan 10 the connecting port on the edge switch was left as a Trunk port with PVID 1 and VLAN 1U.  Which although I'm sure not the correct way worked for us.

I now need both VLAN's to be able to work on the same edge switch and am trying to setup a Trunk between the SG300 and an SG200.  I have tried to configure the SG300 port 49 with a trunk port with 1T and 10T then found out that the SG 200 needed an untagged VLAN so the SG200 would be Port 24 Trunk 1T, 10T and 20U(created so there would be an untagged VLAN and then added to port 49 on the SG300) but as soon as I make both connecting ports Trunk ports the switches can no longer ping each other.  In addition to this I have tried a few other configurations but only had the same results.

I thought as long as the two ports matched both in terms of VLAN and Trunk then the 2 switches can communicate.  I've looked at quite a few tutorials on VLAN's and read the SG200 and 300  documentation so I'm not sure what I'm doing wrong here.

Can anyone help?  

[Tom Watts]

Hi Robert,

The SG200 is a layer 2 switch and the SG300 is defaulted as a layer 2 switch. Lets say your default vlan is 1 for each switch. You may create vlan 10. Then configure the port between each switch as 1u, 10t. This will allow vlan 1 and 10 to communicate. Next, if you assign any port as an access port to vlan 10, anything connecting to a vlan 10 port on the same subnet will talk to each other.

View this picture below; The vlan 10 computers will communicate to each other ONLY on vlan 10. Since this is layer 2 networking, the vlan id will separate the layer 2 traffic while the layer 3 information is separate by subnet. In a fully functional network, the router would need to support the multiple subnet, either through subinterfaces, multiple IP interface or dot1q trunks. If you introduced a router to this mix, the vlan 1 subnet will get to the internet while the vlan 10 subnet will not.

-Tom
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[pektron77]

Hi Thomas, thanks for the quick response!  I configured the switches the way you suggested and the setup worked straight away.  So now I can have different VLAN's on the Edge as well as Core switches.

I still don't understand why my initial configuration didn't work though.  Looking at various tutorials which are available suggested to me that the configuration would work with two vlans such as vlan 10 and 20.  The main difference appears to be that I had tagged vlan 1.  Is best to avoid using the default vlan 1 on cisco small business switches?

Thanks again for your response.

[Tom Watts]

Hi Robert, best practice materials usually avoid using vlan 1. A lot of times vlan 1 is for management only. You can configure a different default vlan or configure multiple vlans and choose one as the untagged pvid while making the other vlan tagged to the trunk port while using my example above, the ports connecting to things such as computers, access member of a particular vlan.

-Tom
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